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[PATCH 0/2] mmc-block: Fine-tuning for mmc_blk_ioctl_copy_from_user()

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  [PATCH 0/2] mmc-block: Fine-tuning for mmc_blk_ioctl_copy_from_user() SF Markus Elfring <elfring@users.sourceforge.net> - 2016-08-19 23:10 +0200
    [PATCH 1/2] mmc-block: Use memdup_user() rather than duplicating its  implementation SF Markus Elfring <elfring@users.sourceforge.net> - 2016-08-19 23:20 +0200
      Re: [PATCH 1/2] mmc-block: Use memdup_user() rather than duplicating  its implementation walter harms <wharms@bfs.de> - 2016-08-20 11:30 +0200
    [PATCH 2/2] mmc-block: Rename jump labels in  mmc_blk_ioctl_copy_from_user() SF Markus Elfring <elfring@users.sourceforge.net> - 2016-08-19 23:20 +0200

#1466683 — [PATCH 0/2] mmc-block: Fine-tuning for mmc_blk_ioctl_copy_from_user()

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Fri, 19 Aug 2016 23:00:23 +0200

A few update suggestions were taken into account
from static source code analysis.

Markus Elfring (2):
  Use memdup_user()
  Rename jump labels

 drivers/mmc/card/block.c | 34 +++++++++++++---------------------
 1 file changed, 13 insertions(+), 21 deletions(-)

-- 
2.9.3

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#1466685 — [PATCH 1/2] mmc-block: Use memdup_user() rather than duplicating its implementation

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Fri, 19 Aug 2016 22:46:38 +0200

* Reuse existing functionality from memdup_user() instead of keeping
  duplicate source code.

  This issue was detected by using the Coccinelle software.

* Delete the integer variable "err" then because the pointer
  variable "idata" should be sufficient to handle return values alone
  in this function.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 drivers/mmc/card/block.c | 26 +++++++++-----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 48a5dd7..6ce9492 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -337,22 +337,21 @@ static struct mmc_blk_ioc_data *mmc_blk_ioctl_copy_from_user(
 	struct mmc_ioc_cmd __user *user)
 {
 	struct mmc_blk_ioc_data *idata;
-	int err;
 
 	idata = kmalloc(sizeof(*idata), GFP_KERNEL);
 	if (!idata) {
-		err = -ENOMEM;
+		idata = ERR_PTR(-ENOMEM);
 		goto out;
 	}
 
 	if (copy_from_user(&idata->ic, user, sizeof(idata->ic))) {
-		err = -EFAULT;
+		idata = ERR_PTR(-EFAULT);
 		goto idata_err;
 	}
 
 	idata->buf_bytes = (u64) idata->ic.blksz * idata->ic.blocks;
 	if (idata->buf_bytes > MMC_IOC_MAX_BYTES) {
-		err = -EOVERFLOW;
+		idata = ERR_PTR(-EOVERFLOW);
 		goto idata_err;
 	}
 
@@ -361,26 +360,19 @@ static struct mmc_blk_ioc_data *mmc_blk_ioctl_copy_from_user(
 		return idata;
 	}
 
-	idata->buf = kmalloc(idata->buf_bytes, GFP_KERNEL);
-	if (!idata->buf) {
-		err = -ENOMEM;
+	idata->buf = memdup_user((void __user *)(unsigned long)
+				 idata->ic.data_ptr,
+				 idata->buf_bytes);
+	if (IS_ERR(idata->buf)) {
+		idata = (void *) idata->buf;
 		goto idata_err;
 	}
-
-	if (copy_from_user(idata->buf, (void __user *)(unsigned long)
-					idata->ic.data_ptr, idata->buf_bytes)) {
-		err = -EFAULT;
-		goto copy_err;
-	}
-
 	return idata;
 
-copy_err:
-	kfree(idata->buf);
 idata_err:
 	kfree(idata);
 out:
-	return ERR_PTR(err);
+	return idata;
 }
 
 static int mmc_blk_ioctl_copy_to_user(struct mmc_ioc_cmd __user *ic_ptr,
-- 
2.9.3

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#1466804 — Re: [PATCH 1/2] mmc-block: Use memdup_user() rather than duplicating its implementation

Am 19.08.2016 23:10, schrieb SF Markus Elfring:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Fri, 19 Aug 2016 22:46:38 +0200
> 
> * Reuse existing functionality from memdup_user() instead of keeping
>   duplicate source code.
> 
>   This issue was detected by using the Coccinelle software.
> 
> * Delete the integer variable "err" then because the pointer
>   variable "idata" should be sufficient to handle return values alone
>   in this function.
> 
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
>  drivers/mmc/card/block.c | 26 +++++++++-----------------
>  1 file changed, 9 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index 48a5dd7..6ce9492 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -337,22 +337,21 @@ static struct mmc_blk_ioc_data *mmc_blk_ioctl_copy_from_user(
>  	struct mmc_ioc_cmd __user *user)
>  {
>  	struct mmc_blk_ioc_data *idata;
> -	int err;
>  
>  	idata = kmalloc(sizeof(*idata), GFP_KERNEL);
>  	if (!idata) {
> -		err = -ENOMEM;
> +		idata = ERR_PTR(-ENOMEM);
>  		goto out;
>  	}
>  
>  	if (copy_from_user(&idata->ic, user, sizeof(idata->ic))) {
> -		err = -EFAULT;
> +		idata = ERR_PTR(-EFAULT);
>  		goto idata_err;
>  	}
>  
>  	idata->buf_bytes = (u64) idata->ic.blksz * idata->ic.blocks;
>  	if (idata->buf_bytes > MMC_IOC_MAX_BYTES) {
> -		err = -EOVERFLOW;
> +		idata = ERR_PTR(-EOVERFLOW);
>  		goto idata_err;
>  	}
>  
> @@ -361,26 +360,19 @@ static struct mmc_blk_ioc_data *mmc_blk_ioctl_copy_from_user(
>  		return idata;
>  	}
>  
> -	idata->buf = kmalloc(idata->buf_bytes, GFP_KERNEL);
> -	if (!idata->buf) {
> -		err = -ENOMEM;
> +	idata->buf = memdup_user((void __user *)(unsigned long)
> +				 idata->ic.data_ptr,
> +				 idata->buf_bytes);
> +	if (IS_ERR(idata->buf)) {
> +		idata = (void *) idata->buf;
>  		goto idata_err;
>  	}
> -
> -	if (copy_from_user(idata->buf, (void __user *)(unsigned long)
> -					idata->ic.data_ptr, idata->buf_bytes)) {
> -		err = -EFAULT;
> -		goto copy_err;
> -	}
> -
>  	return idata;
>  
> -copy_err:
> -	kfree(idata->buf);
>  idata_err:
>  	kfree(idata);
>  out:
> -	return ERR_PTR(err);
> +	return idata;
>  }


This looks strange, returning a freed pointer is a bad idea. I suggest a
idata=NULL after kfree().

re,
 wh

>  
>  static int mmc_blk_ioctl_copy_to_user(struct mmc_ioc_cmd __user *ic_ptr,

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#1466691 — [PATCH 2/2] mmc-block: Rename jump labels in mmc_blk_ioctl_copy_from_user()

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Fri, 19 Aug 2016 22:52:50 +0200

Adjust jump targets according to the Linux coding style convention.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 drivers/mmc/card/block.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 6ce9492..0d83c56 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -346,13 +346,13 @@ static struct mmc_blk_ioc_data *mmc_blk_ioctl_copy_from_user(
 
 	if (copy_from_user(&idata->ic, user, sizeof(idata->ic))) {
 		idata = ERR_PTR(-EFAULT);
-		goto idata_err;
+		goto free_idata;
 	}
 
 	idata->buf_bytes = (u64) idata->ic.blksz * idata->ic.blocks;
 	if (idata->buf_bytes > MMC_IOC_MAX_BYTES) {
 		idata = ERR_PTR(-EOVERFLOW);
-		goto idata_err;
+		goto free_idata;
 	}
 
 	if (!idata->buf_bytes) {
@@ -365,11 +365,11 @@ static struct mmc_blk_ioc_data *mmc_blk_ioctl_copy_from_user(
 				 idata->buf_bytes);
 	if (IS_ERR(idata->buf)) {
 		idata = (void *) idata->buf;
-		goto idata_err;
+		goto free_idata;
 	}
 	return idata;
 
-idata_err:
+free_idata:
 	kfree(idata);
 out:
 	return idata;
-- 
2.9.3

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